Ideal Body Weight: Four Formulas Compared
Ideal body weight (IBW) formulas were originally developed for clinical use — primarily to calculate drug dosages in pharmacology, where the appropriate dose depends on lean body mass rather than total body weight. They have since been widely adopted in general health discussions, though it is important to understand what they do and do not measure. IBW formulas give a single "ideal" weight for a given height and sex, which is a useful reference point but not a precise health target for any individual.
The Devine Formula (1974)
The most widely used IBW formula, developed by B.J. Devine for pharmaceutical dosing. Male: IBW = 50 kg + 2.3 kg × (height in inches − 60). Female: IBW = 45.5 kg + 2.3 kg × (height in inches − 60). It starts at a base weight for 5 feet (60 inches) of height and adds 2.3 kg per additional inch. The formula was calibrated for adults taller than 5 feet; results for shorter individuals should be interpreted cautiously.
The Robinson Formula (1983)
A modification of Devine's formula designed to better fit observed data. Male: IBW = 52 kg + 1.9 kg × (inches − 60). Female: IBW = 49 kg + 1.7 kg × (inches − 60). Robinson's formula tends to give slightly higher estimates than Devine for women and slightly different results for men, particularly at taller heights.
The Miller Formula (1983)
Another Devine derivative: Male: IBW = 56.2 kg + 1.41 kg × (inches − 60). Female: IBW = 53.1 kg + 1.36 kg × (inches − 60). Miller's formula produces higher base weights and a shallower slope, so it tends to give higher estimates for shorter individuals and may underestimate for very tall people.
The Hamwi Formula (1964)
One of the earliest clinical IBW formulas, used in nutrition and dietetics. Male: IBW = 48 kg + 2.7 kg × (inches − 60). Female: IBW = 45.4 kg + 2.3 kg × (inches − 60). Hamwi's formula is still taught in many nursing and dietetics programs and is very close to Devine's for women, while being slightly higher for men.
Limitations of Ideal Weight Formulas
All four formulas share the same fundamental limitation: they were derived from population data and assume a fixed body composition for a given height and sex. They do not account for muscle mass, bone density, age, ethnicity, or fitness level. A well-muscled athlete may be 15 kg heavier than their Devine IBW and have far better health markers than a sedentary person at "ideal" weight. Use these numbers as a rough reference and combine them with other measures like BMI, body fat percentage, and waist-to-height ratio for a more complete assessment.
This calculator is for general reference only and is not medical advice. These formulas have significant limitations for individual health assessment.